Interpretive Summary: This communication documents age-associated pathological changes in these laboratory-confined raccoons. It also reports final observations on experimental transmission of chronic wasting disease (CWD) to raccoons by the intracerebral route. To determine the transmissibility of the CWD agent to raccoons, four kits were inoculated intracerebrally with a brain suspension from mule deer with CWD. Six years past inoculation, none of the CWD-inoculated raccoons had shown clinical signs of neurologic disorder and the experiment was terminated. None of the raccoons were positive for CWD. A few age-related lesions were observed in these raccoons. A couple of them had not previously been reported in raccoons.

Technical Abstract:
This communication documents age-associated pathological changes in these laboratory-confined raccoons (Procyon lotor). It also reports final observations on experimental transmission of chronic wasting disease (CWD) to raccoons by the intracerebral route. To determine the transmissibility of the CWD agent to raccoons, four kits were inoculated intracerebrally with a brain suspension from mule deer with CWD. Two uninoculated kits served as controls. One CWD-inoculated raccoon was humanely killed at 38 months post inoculation (MPI) and one control animal died at 68 MPI. Both animals had lesions that were unrelated to transmissible spongiform encephalopathy (TSE). Six years post inoculation (YPI), none of the three remaining CWD-inoculated raccoons had shown clinical signs of neurologic disorder and the experiment was terminated. Spongiform encephalopathy was not observed by light microscopy and the presence of abnormal prion protein (PrP**d) was not detected by either immunohistochemistry or Western blot techniques. Age-related lesions observed in these raccoons included islet-cell pancreatic amyloidosis (5/6), cystic endometrial hyperplasia in females (3/4), cerebrovascular mineralization (5/6), neuroaxonal degeneration (3/6), transitional cell neoplasm of urinary bladder (1/6) and basophilic myocardial inclusions (4/6). The latter two pathological conditions have not previously been reported in raccoons.